import re

rtn = re.findall('m...e', "cat and mouse")

urlstrs = '''<li><a href="http://news.sina.com.cn/o/2018-11-06/a75.shtml" target="_blank">进博会</a></li>
<li><a href="http://news.sina.com.cn/o/2018-11-06/a76.shtml" target="_blank">大数据</a></li>
<li><a href="http://news.sina.com.cn/o/2018-11-06/a75.shtml" target="_blank">进博会</a></li>'''

urllist = re.findall("http://[a-zA-Z0-9/\.\-]*", urlstrs)

print(urllist)
